Disinfecting and cleansing solution for the human skin



United States Patent DISINFECTIN G AND CLEANSING SOLUTIGN FOR THE HUMANSKIN Adolf Schmitz', Essen, Germany No Drawing. Application July 27,1951, Serial No. 239,003

1 Claim. (Cl. 167-22) This invention relates to disinfecting andcleansing solution for the human skin; and it comprises an aqueousdisinfecting solution for the human skin in which the activedisinfecting agent consists of a water-soluble acid salt of a highmolecular amino acid having the formula:

C12H25 NH CHzCHzNH CHzCHzNH CH2COOH said solution having a pHcorresponding substantially to that of the skin; all as more fullyhereinafter set forth and as claimed.

Surface-active substances are classified by the nature of their electriccharge or the presence (or absence) of ionogenic groups and areaccordingly divided into substances of anionic, cationic, amphoteric ornonionogenic character. Of these substances, the surfaceactivesubstances of anionic and non-ionogenic character are more or lessextensively employed for cleaning of textile materials as well as forbody cleansing, while the cationic surface-active substances have beenfound unsuitable for such purposes. Amphoteric surface-active substanceshave also been suggested for cleaning textile materials and havefurthermore been used as additions in soaps and cosmetics.

Of the four-named types of surface-active substances, the anionicsubstances possess a very slight bactericidal action which isinsufficient for practical purposes. The non-ionogenic substancestotally lack any bactericidal action. The cationic substances, on theother hand, possess a good disinfection action so that such substanceshave primarily found use in the disinfectant field. However, previouslylittle was known concerning the disinfecting action of amphotericsurface active substances.

In disinfection, for example, the disinfection of the hands, it is ofspecial importance that the disinfection is assisted by good cleansingof the skin to remove the adhering germs. It is therefore necessary insurgery that the disinfection of the hands with cationic-activesubstances, for example, quaternary ammonium compounds, be preceded by acleansing with anionic surface-active agents, which for practicalpurposes were the only substances suitable for thorough cleansing. Thismethod, which is necessary because of the insufficient cleansing actionof cationic surface-active agents, not only has the disadvantage thattwo different substances must be employed successively but also has thedefect that the bactericidal action of the cationic surface-activesubstance is destroyed by anionic surfaceactive substances. Consequentlythe soap or other anionic surface-active agent which remains after thefirst treatment renders the disinfection of the second treatment withcationic surface active agents illusionary.

This defect of the quaternary ammonium compounds, which was recognizedsoon after the discovery of their bactericidal action, has led to manyattempts to improve their washing or cleansing action, and consequently,for example, mixtures of quaternary ammonium compounds and salts of highmolecular amines have been recommended. Furthermore, alkylatedpolyalkylenepolyamines have been described as good washing anddisinfecting means. However, a satisfactory solution to this problem hadpreviously not been achieved.

The cleaning action of a surface-active agent upon inanimate materials,such as textiles, as well as the bactericidal activity of substancesupon such materials does not in itself serve as a true indication oftheir suitability for cleansing and disinfecting the human body.

Most surface-active agents which have been found suited for cleaningmaterials, such as textiles, have been found practically unsuited asbody-cleansing agents. Whereas in the cleaning of textiles all particlesof dirt and grease must be completely removed, in some cases with theassistance of strong mechanical action, careful treatment is required inthe cleansing of the skin and excessive removal of fat from the skin andswelling are to be avoided. The natural prophylatic functions of theskin, such as the acid coating which hinders the growth of bacteria andtheir penetration into the pores, the sebaceous matter upon which thesmoothness and suppleness of the skin depend and the horny substance ofthe upper layer of the skin which resists abrasion, should remainundamaged as a consequence of cleansing, as otherwise disadvantageousefiects may be produced upon the entire organism. Thus, for example, ithas been found that the sulfuric acid esters of higher fatty acids,which are very suitable for wash ing textiles and other inanimatematerials, cannot be employed as skin-cleansing agents as they causevery considerable roughening and cracking of the skin and, in this way,actually favor the accumulation of dirt and bacteria on the skin washedtherewith.

Consequently, the range of substances which can be employed forbody-cleansing purposes is very limited. Previously practically onlynormal soaps have been employed for skin cleansing and for the care ofthe body, while other synthetic media which are normally employed in thetextile industry and which have been proposed for cleansing the skin andcare of the body have not been found well suited therefor.

While cationic surface-active agents, as has been indicated above,having strong bactericidal action, they are not without their drawbackswhen employed for disinfection of the body. Their bactericidal activityis substantially diminished in the presence of albumen. Furthermore,cationic active substances such as the quaternary ammonium compoundscause precipitation in albumen solutions, which evidently is one of thereasons that they are not especially compatible with the skin and easilycause reddening and irritation of the skin.

It is an object of the present invention to provide novel compositionswhich simultaneously have excellent body cleansing and disinfectingproperties.

In accordance with the invention it was unexpectedly found that acertain class of amphoteric surface-active agents possesses not onlygood body cleansing but also good disinfecting properties when employedin the form of aqueous solutions of their salts with organic orinorganic acids. These amphoteric surface active agents are the watersoluble acid salts of a high molecular amino acid having the formula:

C12H25 NH CHzCHzNH- CHzCHzNH CHzCOOH These compounds have unexpectedlybeen found, contrary to most synthetic surface-active cleaning agents,not only to be admirably suited for body-cleansing purposes but also tosurpass all previously used and known cleansing agents in this respect.

As the amphoteric substances in accordance with the invention can beadjusted to the pH of the skin, swelling of the skin such as, forexample, occurs with the alkaline reacting normal soaps can be avoided.Consequently the amphoteric substances do not alter the pH of the skincleansed therewith. Furthermore, even with constant use they do not leadto roughening of the skin as, because of their amphoteric character,they do not, as is the case with fatty alcohol sulfonates, disturb thedissociation equilibrium of the similarly composed skin albumen.

The excellent dirt-carry capacity of the amphoteric surface-activeagents in accordance with the present invention is a further markedadvantage of such substances.

The dirt-carrying capacity of the surface-active agents in accordancewith the invention surpasses that of both the cationic and the anionicgroups of surface active substances, as is shown by the determinationthereof by a method of E. M. C. Liesegang (Fette und Seifen 1940, volume47, page 458). This method permits an exact comparison of differentsubstances and gives a number which is lower as the dirt-carryingcapacity of the tested substance is higher. Thus the following numberswere obtained for substances of comparable chemical structure:

Dirt-carrying capacity of the 10% solution according Amphotertcsurface-active substances to Llesegang of the type according to theinvention 10-15 Cationic surface-active substances 20-25 Anionicsurface-active substances 15-30 The dirty-carrying capacity ofsurface-active substances is of prime importance in body cleansing.Body-cleansing agents having a low dirt-carrying capacity can removedirt particles from the skin but readily allow them to fall back whendiluted with water, as occurs during rinsing. If the poor dirt carriersare good wetting agents, as is the case, for example, with sulfonates,the dirt is actually not removed from the skin but is washed into thewetted fine crevices and hair outlets in the skin, accumulates therein,and can be removed only with difiiculty, generally only by themechanical action of a brush.

The amphoteric body-cleansing agents according to the invention have avery strong disinfecting action and are able to destroy bacteria in ashort time even when greatly diluted. Contrary to the cationicsurface-active agents, such as the quaternary ammonium compounds, theirbactericidal activity is only slightly affected by the presence ofalbumens and even in strong albumen solutions, such as blood serum, theyhave only a slightly lowered activity. Furthermore, the amphotericsubstances in accordance with the invention are very compatible with theskin and have substantially no irritating effect.

The following example will serve to illustrate the manufacture ofbody-cleansing agents in accordance with the invention.

Example 1 mol of monodecyldiethylenetriamine was reacted with a solutionof the sodium salt of monochloracctic acid to produce an amino acid ofthe following formula:

An aqueous solution of this acid was treated with an equivalent oflactic acid to produce the corresponding lactate.

The acid salts of the above amino acid have excellent cleansing anddisinfecting properties. Preferably they are prepared in the form oftheir aqueous solutions, the pH of which is adjusted to about that ofthe skin. Preferably they are not combined with fats or oils or soaps,as the presence of these compounds reduces their disinfecting action.

This application is a continuation-in-part of my application SerialNumber 115,566, filed on September 13, 1949 and now abandoned.

I claim:

An aqueous disinfecting and cleansing solution for the human skin inwhich the active disinfecting agent consists of a water-soluble acidsalt of a high molecular amino acid having the formula:

O to that of the skin.

References Cited in the file of this patent UNITED STATES PATENTSSchoeller et al. Dec. 28, 1937 Guild Dec. 1, 1942 OTHER REFERENCESHyamines 1622 and 10-x, Rohm & Haas Co., 1947, pp. 4-5.

